Line‐Field Confocal Optical Coherence Tomography: A Diagnostic Tool Facilitating the Diagnosis of Sweet's Syndrome. A Case Report

ABSTRACT Sweet's syndrome is a rare neutrophilic dermatosis characterized by an acute onset of erythematous and infiltrative lesions. Diagnosis is based on clinical, histopathological, and laboratory findings. We propose that non‐invasive skin imaging techniques, such as line‐field confocal optical coherence tomography (LC‐OCT), may be beneficial for early diagnosis and appropriate treatment of the disease. A 59‐year‐old patient was admitted to the Dermatology Department due to the presence of erythematous‐vesicular plaques located on the upper limbs, neck, and chest for 4 days. The onset of skin lesions was preceded by an upper respiratory tract infection. LC‐OCT skin imaging was performed on selected lesions of the patients' left forearm. LC‐OCT findings included: edema of papillary dermis, infiltrate of big hyper‐reflective cells within papillary dermis and epidermis. Then, a 4‐mm punch biopsy was taken from the same lesion. Histopathological examination of the skin lesions showed swelling of the papillary layer of the skin, a mixed cellular inflammatory reaction below, with prominent neutrophils, which correlated directly with LC‐OCT findings. Based on the criteria proposed by Dreish, the diagnosis of Sweet's syndrome was established. Treatment with cefuroxime and methylprednisolone resulted in significant improvement, and was followed by oral prednisone in out‐patient's clinic. Complete remission of the lesions was achieved. The patient was referred for an urgent hematology consultation. The use of non‐invasive optical imaging techniques, such as LC‐OCT, in Sweet's syndrome may aid in early diagnosis and initiation of appropriate treatment while awaiting histopathological examination.